First time building a PC and an confused with my GPU installation. I have a Zotac GeForce gtx1080 amp! Edition, and I'm using an EVGA 850 BQ PSU. The GPU has two 8 pin inputs and my pcie cable has a 6+2 and a 6. Do I plug the 6 into the 8 pin inputs or attach another cable to my PSU and hook another 6+2 cable into it? Thanks!